2D X-Ray Radiography of Imploding Capsules at the National Ignition Facility

J. R. Rygg(Lawrence Livermore National Laboratory), O. S. Jones(Lawrence Livermore National Laboratory), J. E. Field(Lawrence Livermore National Laboratory), M. A. Barrios(Lawrence Livermore National Laboratory), L. R. Benedetti(Lawrence Livermore National Laboratory), G. W. Collins(Lawrence Livermore National Laboratory), D. C. Eder(Lawrence Livermore National Laboratory), M. J. Edwards(Lawrence Livermore National Laboratory), J. L. Kline(Los Alamos National Laboratory), J. J. Kroll(Lawrence Livermore National Laboratory), O. L. Landen(Lawrence Livermore National Laboratory), T. Ma(Lawrence Livermore National Laboratory), A. Pak(Lawrence Livermore National Laboratory), J. L. Peterson(Lawrence Livermore National Laboratory), Kumar Raman(Lawrence Livermore National Laboratory), R. P. J. Town(Lawrence Livermore National Laboratory), D. K. Bradley(Lawrence Livermore National Laboratory)
Physical Review Letters
May 12, 2014
10.1103/physrevlett.112.195001
Cited by 182

Abstract

First measurements of the in-flight shape of imploding inertial confinement fusion (ICF) capsules at the National Ignition Facility (NIF) were obtained by using two-dimensional x-ray radiography. The sequence of area-backlit, time-gated pinhole images is analyzed for implosion velocity, low-mode shape and density asymmetries, and the absolute offset and center-of-mass velocity of the capsule shell. The in-flight shell is often observed to be asymmetric even when the concomitant core self-emission is round. $\mathrm{A}\ensuremath{\sim}15\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ shell asymmetry amplitude of the ${Y}_{40}$ spherical harmonic mode was observed for standard NIF ICF hohlraums at a shell radius of $\ensuremath{\sim}200\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ (capsule at $\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}$ radial compression). This asymmetry is mitigated by a $\ensuremath{\sim}10%$ increase in the hohlraum length.

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